Publications

Biohybrid robots, or bio-bots, integrate living and synthetic materials following a synergistic strategy to acquire some of the unique properties of biological organisms, like adaptability or bio-sensing, which are difficult to obtain exclusively using artificial materials. Skeletal muscle is one of the preferred candidates to power bio-bots, enabling a wide variety of movements from walking to swimming. Conductive nanocomposites, like gold nanoparticles or graphene, can provide benefits to muscle cells by improving the scaffolds' mechanical and conductive properties. Here, boron nitride nanotubes (BNNTs), with piezoelectric properties, are integrated in muscle-based bio-bots and an improvement in their force output and motion speed is demonstrated. A full characterization of the BNNTs is provided, and their piezoelectric behavior with piezometer and dynamometer measurements is confirmed. It is hypothesized that the improved performance is a result of an electric field generated by the nanocomposites due to stresses produced by the cells during differentiation. This hypothesis is backed with finite element simulations supporting that this stress can generate a non-zero electric field within the matrix. With this work, it is shown that the integration of nanocomposite into muscle-based bio-bots can improve their performance, paving the way toward stronger and faster bio-hybrid robots.

JTD Keywords: Bio-bots, Biohybrid robots, Biomaterials, Boron nitride nanotubes, Cells, Cytotoxicity, Differentiation, Myoblasts, Skeletal muscle tissue, Skeletal-muscle, Stimulation

Polarized hydroxyapatite (p-HAp), a calcium phosphate catalyst obtained at high temperature under intense electric field, has been used for the synthesis of ammonium starting from N2 and liquid water at low pressure (<6 bar) and temperatures below 120 C. The success of the nitrogen fixation process has been demonstrated by isotope labelling experiments using 15N2. Considering the optimal reaction conditions for the production of ammonium, the yield is as high as 154.6 +/- 25.8 mu mol/g of catalyst. The proposed synthesis exhibits three important advantages for its utilization in green chemistry environmental processes related to the recycling of polluted air. These are: i) the catalysts converts CO2 into valuable chemical products in addition of transforming N2 in ammonium; ii) the final energy balance is very favorable since no external electrical field is necessary to promote nitrogen and carbon fixation reactions; and iii) products are easily transferred to water favoring their extraction and avoiding the saturation of the catalyst.

JTD Keywords: Adsorbed nitrogen, Air pollution, Amino-acids, Electrophotosynthesis, Environmental process, Facile synthesis, Fixation, Functionalization, Hydroxyapatite, Nitride, Nitrogen reduction, Polarized catalyst

New silicon nitride coated optical gratings were tested by means of Optical Waveguide Lightmode Spectroscopy (OWLS). A thin layer of 10 nm of transparent silicon nitride was deposited on commercial optical gratings by means of sputtering. The quality of the layer was tested by x-ray photoelectron spectroscopy and atomic force microscopy. As a proof of concept, the sensors were successfully tested with OWLS by monitoring the concentration dependence on the detection of an antibody-protein pair. The potential of the Si3N4 as functional layer in a real-time biosensor opens new ways for the integration of optical waveguides with microelectronics.

JTD Keywords: Silicon nitride, Optical gratings, Waveguide, Biosensor

In this work we report the fabrication and characterization of a label-free impedimetric immunosensor based on a silicon nitride (Si 3N 4) surface for the specific detection of human serum albumin (HSA) proteins. Silicon nitride provides several advantages compared with other materials commonly used, such as gold, and in particular in solid-state physics for electronic-based biosensors. However, few Si 3N 4-based biosensors have been developed; the lack of an efficient and direct protocol for the integration of biological elements with silicon-based substrates is still one of its the main drawbacks. Here, we use a direct functionalization method for the direct covalent binding of monoclonal anti-HSA antibodies on an aldehyde-functionalized Si-p/SiO 2/Si 3N 4 structure. This methodology, in contrast with most of the protocols reported in literature, requires less chemical reagents, it is less time-consuming and it does not need any chemical activation. The detection capability of the immunosensor was tested by performing non-faradaic electrochemical impedance spectroscopy (EIS) measurements for the specific detection of HSA proteins. Protein concentrations within the linear range of 10 -13-10 -7M were detected, showing a sensitivity of 0.128ΩμM -1 and a limit of detection of 10 -14M. The specificity of the sensor was also addressed by studying the interferences with a similar protein, bovine serum albumin. The results obtained show that the antibodies were efficiently immobilized and the proteins detected specifically, thus, establishing the basis and the potential applicability of the developed silicon nitride-based immunosensor for the detection of proteins in real and more complex samples.

JTD Keywords: Aldehyde, Electrochemical impedance spectroscopy, Human serum albumin, Immunosensor, Silicon nitride, Bovine serum albumins, Chemical reagents, Complex samples, Covalent binding, Detection capability, Electrochemical impedance, Electrochemical impedance spectroscopy measurements, Functionalizations, Human serum albumins, Impedimetric immunosensors, Label free, Limit of detection, Linear range, Protein concentrations, Silicon-based, Specific detection, Aldehydes

Silicon nitride surfaces are modified with a triethoxysilane aldehyde self-assembled monolayer for the direct immobilization of monoclonal antibodies and the detection of human serum albumin proteins, without any activation requirements. Surface modification and the specific recognition interaction between the HSA protein and its associated antibody are studied by fluorescence microscopy and atomic force microscopy.

JTD Keywords: Aldehyde, Human serum albumin, Immunosensors, Microcontact printing, Silicon nitride